In addition to the common mechanically operating epilators, devices for removing body hair, which irradiate the skin surface in particular with electromagnetic irradiation of a suitable wavelength, in particular laser light or pulsed light, so as to damage the hair roots and follicles, which are embedded in the skin or which are located underneath the skin, respectively, are used to an increasing extent to remove body hair. Wavelengths in the range of from 600 to 1100 nm and pulse lengths in the range of from 20 to 500 ms can hereby be used in particular, so that the hair and the immediately surrounding tissue layers are subjected to a photothermolysis, by means of which the structure of the hair and follicle cells can be changed and the hair growth can be reduced.
Due to the fact that high energy densities in the range of from 1 to 50 J/cm2 are used hereby, proper use is required. Such domestic equipment thus requires special safety measures.
Concerning this matter, different safety measures have already been proposed. US 2005/0049657 and US 2005/0045189 in each case combine equipment for irradiating body skin or for reducing body hair, respectively, where the operator can set different device parameters so as to adjust the irradiation to the personal requirements. To avoid dangerous operating errors, the devices comprise a safety device, which, in response to the corresponding setting of a device parameter, has the effect that upper limits, which correspond to other device parameters, cannot be exceeded so as to limit the total applied energy content (in particular per time and per area). US 2005/0177139 A1 describes a device for removing body hair, where the speed of movement, at which the working head is moved across the skin surface, is recorded by means of a roller, which serves as a speed sensor and which rolls on the skin surface. The irradiation intensity is changed as a function of the recorded speed of movement, the irradiation intensity is reduced in particular when the working head is moved too slowly, so as to avoid an excessive irradiation of the skin surface. A similar safety device is described in US 2006/0020260, which also records the speed of movement of the working head by means of a speed sensor and which correspondingly controls the laser irradiation source. The corresponding sensor is thereby preferably to be embodied so as to operate in an optical manner and is to simultaneously record the proximity of the skin to the sensor so that the laser source can be turned off as soon as the working head with the sensor is moved too far away from the skin, which is to be treated. A hair removal or hair reducing device, respectively, comprising a similar safety device is described in WO 2006/005443.
A device for the application of light onto the skin is described in WO 2005/009266 A1, which encompasses a treatment head comprising a recess, from which the light is emitted and in which the air pressure can be reduced by means of a pump. The device also encompasses a pressure measuring unit, which measures the air pressure in the recess. Above an air pressure threshold value, a control means prevents activation of the light emission as such pressure means that the device is not sealed against the skin surface to be irradiated. The fact that the skin is thereby sucked into the recess also leads to an improvement of the characteristics of the skin with reference to the absorption of light irradiation.